如何使用 ES6 从对象数组中删除重复项？

Question

I'm wondering what the best method would be to merge 2 array of objects itemsA and itemsB . The data once merged should be in mergedList .

Criteria:

1. Items with source='STAPLE' should not repeat in merged array.
2. Items with any other source may repeat. For exampele an item name: 'Ball' by source: 'USER' may exist twice.

itemsA has 6 items, itemsB has 7 items and mergedList should have 11 items

let itemsA = [
{name: 'Milk', source: 'STAPLE'},
{name: 'Bread', source: 'AD'},
{name: 'Egg', source: 'STAPLE'},
{name: 'Ball', source: 'USER'},
{name: 'Pasta', source: 'STAPLE'},
{name: 'Coke', source: 'AD'}];
let itemsB = [
{name: 'Milk', source: 'USER'},
{name: 'Bread', source: 'AD'},
{name: 'Egg', source: 'STAPLE'},
{name: 'Ball', source: 'USER'},
{name: 'Mango', source: 'USER'},
{name: 'Pasta', source: 'STAPLE'},
{name: 'Coke', source: 'USER'}]

mergedList should equal to

let mergedList = [
{name: 'Milk', source: 'STAPLE'},
{name: 'Bread', source: 'AD'},
{name: 'Egg', source: 'STAPLE'},
{name: 'Ball', source: 'USER'},
{name: 'Pasta', source: 'STAPLE'},
{name: 'Coke', source: 'AD'}] 
{name: 'Milk', source: 'USER'},
{name: 'Bread', source: 'AD'},
{name: 'Ball', source: 'USER'},
{name: 'Mango', source: 'USER'},
{name: 'Coke', source: 'USER'}]   ];

Answer 1

function merge(itemsA, itemsB) {
  let merged = [];
  itemsA.concat(itemsB).reduce((stapleSet, obj) => (obj.source != "STAPLE") ?
  (merged.push(obj), stapleSet) : 
  (stapleSet.has(obj.name) || merged.push(obj), 
  stapleSet.add(obj.name), stapleSet), new Set());

  return merged;
}

• get two arrays.
• create a merged array to push objects to.
• concatenate the two item arrays together.

• reduce the concatenated array - if the object source is staple and not in stapleSet add the name of the object to stapleSet -- Set objects only allow one of each entry -- then push object to merged array. Otherwise push object to he merged array.

• return the merged array from the function.

 let itemsA = [ {name: 'Milk', source: 'STAPLE'}, {name: 'Bread', source: 'AD'}, {name: 'Egg', source: 'STAPLE'}, {name: 'Ball', source: 'USER'}, {name: 'Pasta', source: 'STAPLE'}, {name: 'Coke', source: 'AD'}]; let itemsB = [ {name: 'Milk', source: 'USER'}, {name: 'Bread', source: 'AD'}, {name: 'Egg', source: 'STAPLE'}, {name: 'Ball', source: 'USER'}, {name: 'Mango', source: 'USER'}, {name: 'Pasta', source: 'STAPLE'}, {name: 'Coke', source: 'USER'}]; function merge(itemsA, itemsB) { let merged = []; itemsA.concat(itemsB).reduce((stapleSet, obj) => (obj.source != "STAPLE") ? (merged.push(obj), stapleSet) : (stapleSet.has(obj.name) || merged.push(obj), stapleSet.add(obj.name), stapleSet), new Set()); return merged; } console.log( merge(itemsA, itemsB) );

Edit : If-Else formatting for OP

function merge(itemsA, itemsB) {
  let merged = [];
  itemsA.concat(itemsB).reduce((stapleSet, obj) => {
    if (obj.source != "STAPLE") {
      merged.push(obj);
      return stapleSet;
    } else {
      if (stapleSet.has(obj.name)) {
        return stapleSet;
      } else {
        merged.push(obj);
        stapleSet.add(obj.name);
        return stapleSet;
      }
    }
  }, new Set());
  return merged;
}